基于塘内循环自净的河蟹生态养殖系统设计与试验

为了提高河蟹养殖品质和养殖池塘水质净化能力,该研究提出了一种通过养殖池塘内部结构改造实现池塘水体内部循环自净的技术,并设计了一套针对河蟹的生态养殖系统。应用软围隔将养殖塘划分为两个相对独立的功能区(养殖区和自净区),设计了浮式气提推水装置和射流装置作为塘内水循环动力系统,在推水装置的作用下,养殖区的水体流入自净区,经过滤、吸附、杀菌及降温等环节重新回到养殖区,形成"九分养蟹一分养水"的河蟹循环自净生态养殖模式。在崇明宝岛蟹业面积约为9 600 m~2的河蟹养殖池塘进行实施和试验,试验表明:合理配置气提推水装置可实现河蟹养殖池塘水体日循环2次以上;试验塘循环自净状态相较静水状态,水温均衡度提高10.17%,下层溶解氧水平提高18.57%,氨氮平均质量浓度下降19.2%;同时,养殖效果抽样对比显示试验塘200 g以上公蟹和150 g以上母蟹较对照塘分别增加了45%和35%。该研究设计的塘内循环自净的河蟹生态养殖系统能较好地净化养殖水体,有利于河蟹的生长,可为河蟹池塘生态高效养殖模式的构建和推广提供参考。

Design and experiment on crab ecological culture system using internal circulation and self-purification in a pond

Eriocheir sinensis (Chinese mitten crab) is one of the most important freshwater aquaculture species in China. Pond farming has widely been applied in several Eriocheir sinensis aquaculture modes. In this study, an improved Eriocheir sinensis ecological aquaculture system was proposed for better purification ability of pond water using the core technology of internal circulating and self-purification. Soft barricading was utilized to divide the aquaculture pond into two relatively independent functional areas, including the aquiculture and water self-purification areas. The specific procedure was as follows. 1) The air lift, water pushing and jet device were designed to serve as the power source of water circulation in the aquiculture area. The air lift and water pushing device pushed the water from the self-purification to the aquiculture area, where the content of dissolved oxygen improved with a relatively low fluctuation of water temperature in the pond. The jet device created microfluidics in the dead corner of a pond or the area with dense aquatic plants. 2) The water self-purification area was designed to serve as the water circulation reverse-flow system, aiming at suspended solid filtration, chemistry absorption, sterilization, and water cooling in the backflow of internal circulation. 3) A field test was carried out in the Shanghai Baodao Crab Company to evaluate the ecological aquaculture system. The experimental pond with an area of 1 hm2 was located at 31?74?N, 121?23?E. Two parts of a pond were divided into an ecological aquaculture system, including the aquiculture area of 8 644 m2 and the water self-purification area of 956 m2. The results were showed as following: 1) The flow rate of each air lift and water pushing device was tested to be 187 m3/h. The pond water was exchanged more than twice a day. 2) The standard deviation of temperature fluctuation was lower than that of the traditional mode. The average value for equilibrium degree of water temperature was 0.893, 10.17% higher than that in the traditional mode with 0.811 equilibrium degree of water temperature. 3) The average value of dissolved oxygen in the deepwater layer (below 70 cm) was 4.498 mg/L, 18.57% higher than that in the traditional mode. 4) The average concentration of ammonia nitrogen was 19.2% lower than that of the traditional mode. Consequently, the water quality of the ecological aquaculture system was much better than that of the traditional mode. 200 crab samples (100 female crabs and 100 male ones) were randomly selected from the test and traditional pond (control group). The comparison result showed that the yield of crab increased 17.9% using the ecological aquaculture system, where the male crabs over 200 g increased 45%, and the female crabs over 150 g increased 35.0%. The finding can provide a great reference to Eriocheir sinensis aquaculture industry.